Enzymatic Hydrolysis

The first application of enzymes to wood hydrolysis in an ethanol process was to simply replace the cellulose acid hydrolysis step with a cellulase enzyme hydrolysis step. This is called separate hydrolysis and fermentation. An important process modification made for the enzymatic hydrolysis of biomass was the introduction of simultaneous saccharification and fermentation (SSF), which has recently been improved to include the cofermentation of multiple sugar substrates. In the SSF process, cellulase and fermenting microbes are combined. As sugars are produced, the fermentative organisms convert them to ethanol. The enzymatic hydrolysis process will be used in Iogen/Petro Canada's Ottawa, Canada project and is being explored for BCI's Gridely project. Because Biomass Program researchers see the current high cost of cellulase enzymes as the key barrier to economical production of bioethanol from lignocellulosic material, the Biomass Program has been working with the two largest global enzyme producers, Genencor International and Novozymes. The objective of this collaboration is to achieve a ten- to fifty-fold reduction in the cost of these enzymes as a key step in making sugar platform technology competitive with fermentation of starch or sugar crops to enable commercialization.

For Further Reading

"Unraveling the Structure of Plant Life," Excerpt from National Renewable Energy Laboratory 2004 Research Review, 2nd Edition (PDF 622 KB) Download Adobe Reader.
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Fermentation Background